Motion pictures are images in 2-dimensions. However, several methods have been developed for providing the illusion of depth or 3-dimensions in motion pictures. These include the Anaglyph, Intru3D (also called ColorCode 3D), IMAX (Polaroid), and shutter glasses.
Anaglyph 3-Dimensional Illusion
“Anaglyph” refers to the red/blue (red/cyan or red/green) glasses that are used in movies, comic books cereal packets etc. The glasses consist of nothing more than one piece of transparent blue plastic and one piece of transparent red plastic. These glasses are easy to manufacture and have been around since the 1920s.
An anaglyph stereo picture starts as a normal stereo pair of images, two images of the same scene, shot from slightly different positions. One image is then made all green/blue and the other is made all red, the two are then seen together.
When the image is viewed through the glasses the red parts are seen by one eye and the other sees the green/blue parts. The visual cortex of the brain fuses this into perception of a three-dimensional scene or composition. This effect is fairly simple to do with photography, and extremely easy to do on a PC, and it can even be hand-drawn. The main limitation of this technique is that because the color is used in this way, the true color content of the image is usually lost and the resulting images are usually in black and white. As the colors compete for dominance they may appear unstable and monochromatic. A few images can retain a resemblance to their original color content, but the photographer has to be very selective with color and picture content.
Intru3D—Intel
Intel's Intru3D uses the ColorCode 3D method that is an update to the more familiar Anaglyph method of 3D stereoscopy. It is similar to the Anaglyph method of stereoscopy but rather than make one image green/blue and the other image red, Intru3D records the two images as amber and blue. This provides generally truer color than typical Red/Blue anaglyphs, particularly where Red image components are concerned.
IMAX (Polaroid) 3-Dimensional Illusion
IMAX creates the illusion of 3-dimensional depth by recording the motion pictures on two separate rolls of film with two camera lenses to represent the left and right eyes. These lenses are separated by an interocular distance of about 2.5 inches that is the average distance between a human's eyes. By recording on two separate rolls of film for the left and right eyes, and then projecting them simultaneously, IMAX can create a 3-Dimensional illusion for viewers.
IMAX uses either of two different methods to create the 3D illusion in the theatre. The first method relies on polarization. During projection, the left eye image is polarized in one direction and the right eye image polarized perpendicular to the left eye image as they are projected on the IMAX screen. By wearing special viewing glasses with lenses polarized in their respective directions to match the projection, the left eye image can be viewed only by the left eye since the polarization of the left lens will cancel out that of the right eye projection, and the right eye image can be viewed only by the right eye since the polarization of the right lens will cancel out that of the left eye projection.
IMAX also uses another method—shutter glasses—for 3D viewing. This method of 3D projection involves the use of LCD shutter glasses that use similarly polarized lenses for both eyes. The left and right eye images are projected on the viewing screen in alternate frames. These LCD shutter glasses are synchronized to the projector. The projector displays the left and right images that are momentarily viewed by the appropriate eye by allowing that LCD lens to become transparent while the other remains opaque. That is when the left eye frame is projected on the screen, the left lens of the shutter glasses becomes transparent and the right lens of the shutter glasses becomes opaque. When the next frame is projected on the screen—a frame for the right eye—the left lens becomes opaque and the right lens becomes transparent.
In both the IMAX 3D systems only the correct eye is allowed to view the correct image while the other eye is ‘blinded’. The ‘transparent’ state is actually quite dark, and occludes about 40% of the projected light to the viewing eye while the non-viewing eye is supposed to view no image at all.
Shutter Glasses
Different formulations of shutter glasses have been implemented over the last few decades, but without much large-scale commercial success. A shutter glasses solution generally require two images for each image of video, with shutter covering or uncovering each eye of the viewer. This allows one eye to see, then the other, with the shutters timed and synchronized with the video so that each eye only sees the image intended for it.
Some shutter glass systems are wired to a control device while some shutter glass systems use wireless infrared signaling to control the state of the lenses.
CrystalEyes is the name of a stereoscopic viewing product that was produced by the StereoGraphics Corporation of San Rafael, Calif. They are lightweight, wireless liquid crystal shuttering eyewear that are used to allow the user to view alternating field sequential stereo images. The source of the images alternately displays a left-eye view followed by a right-eye view. CrystalEyes' shutters can block either of the user's eyes so that only images appropriate for each eye are allowed to pass. A wireless infrared communications link synchronizes the shuttering of the eyewear to the images displayed on the monitor or other viewing screen. CrystalEyes shutter glasses, weigh only 3.3 ounces, use two 3V lithium/manganese dioxide batteries, and have a battery life of 250 hours. This demonstrates the robustness and potential of any viewer glass solution.
Because shutter glasses only expose each eye to every other frame, the refresh rate of the video is effectively cut in half. On a TV with refresh rates of 30 frames per second (for an NTSC TV) or 25 frames per second (for a PAL TV), this is hard on the eyes because of the continual flicker. This problem is eliminated with higher refresh rates, such as on PC monitors.
The most recent innovation in shutter glasses from the RealD Corporation of Hollywood, Calif. synchronize dual-image 3-D movies to refresh rates of 120-240 frames per second and are the basis for the 3D TVs on the market today.
Each of these well-known 3D systems is a dual-image system meaning that each eye views different images. The 3Deeps Viewing Spectacles and systems described in previous related patent applications and in this patent application is a single-image system meaning the same single image is viewed by both eyes. This is a totally different approach to producing the illusion of 3D. Motion pictures prepared for viewing by a dual-image 3D system cannot be viewed using 3Deeps, and 3Deeps movies cannot be viewed by any of the dual-image systems for 3D.